The definition of a quadratic equation is one in which one of the terms is raised to the second power (squared).
An example of a quadratic equation is 2x² + 4x + 4.
An equation that employs the variable x having the general form ax2 + bx + c = 0, where a, b, and c are constants and a does not equal zero; that is, the variable is squared but raised to no higher power.
An equation in which the second power, or square, is the highest to which the unknown quantity is raised.
(mathematics) A polynomial equation of the second degree.